Re: [hpoj-devel] LCD encoding

[Dmitry V. <dv...@ro...>]

Hi Joe,

On Friday 09 April 2004 04:51, Joe Piolunek wrote:
> Can you supply more info about the issue?  Which peripherals (that
> you know of) exhibit the problem?  Do the cyrillic characters display
> correctly on the device's built-in LCD screen (under Linux)?  Are only
> a few characters displayed incorrectly? When characters are not
> displayed correctly, do other characters appear in their place, or do=20
> they simply not appear?

Well, this problem was reported on a Russian-speaking mailing list. The=20
guy used xojpanel to view the LCD of a Color LaserJet 4550. All Latin
characters are displayed properly, Cyrillic ones -- not. I'm sure the=20
device itself has no such problems and the problem lies elsewhere. It=20
is also neither font related nor caused by the built-in translation of=20
special characters.

> Unfortunately, I'm not very familiar with internationalization issues.
> A little reading turned up the lesstif/Motif/openMotif function
> "XmStringCreateLocalized(text)", which at first glance looks like it
> might be possible to use it as a conversion wrapper for the strings
> 'Line1' and 'Line2' in xojpanel.cpp, but I'm really just guessing at
> this point.=20

Unicode QStrings Line1 and Line2 currently get their values from the raw
string obtained from the device (with special symbols translated). From=20
the output of 'ptal-hp display' we have found out that ISO8859-5 is=20
used for Cyrillic text in the device. Now what we need is to explicitly=20
specify the encoding of the text received from the device so that it=20
will be converted to Unicode correctly. In this regard xojpanel.cpp=20
could be changed as follows:

QTextCodec *codec =3D QTextCodec::codecForName(deviceEncoding);
// in our case deviceEncoding =3D=3D "iso8859-5"
Line1 =3D codec->toUnicode(tmpString.remove( length - spaces, spaces ));

I suggest adding an extra command line option to xojpanel like=20
=2Ddeviceenc <encoding> to set the value of deviceEncoding manually. The
default would be iso8859-1 then. Of course it would be nice to be able=20
to retrieve the encoding from the device itself based on some kind of=20
PML object that is set to a language it's using for the LCD. But for=20
now that's just dreams :-)

Anyway, even in the proposed solution there is a catch related to those
special characters that HP uses for arrows and such. The built-in
translation maps them to e.g. '>>' that simply doesn't exist in=20
iso8859-5. Therefore, the above mentioned convertion from iso8859-5 to=20
Unicode would corrupt the arrows and show something weird instead of=20
them. I'll try to come up with something to overcome this.

> Is there any other encoding that could be used to display cyrillic?
> If iso8859-5 contains all of the needed characters for russian and
> russian-related languages, it probably would be the one used.

KOI8-R and CP1251 are much more common. And though ISO8859-5 is called=20
an official standard, it's almost never used :-)

Yes, and one more thing not really connected with encodings. Messing=20
with xojpanel's source I found out that my PSC 2110 uses a special=20
character 0x15 for the right arrow. Previously xojpanel showed no right=20
arrows for this device at all, though they were present on the LCD.=20
Adding 0x15 to the translation map fixed that.

=2D-=20
Dmitry Vukolov